EAS systems can be used to prevent unauthorized removal of merchandise from stores or retail settings, and prevent removal of books or other lending media from libraries without the item first being checked out. EAS systems typically include a detection system, often made of two side gates between which an individual must pass to exit a store or library. The gates generate an electromagnetic field that is used to excite a response from a security tag attached to the merchandise, book or media. A variety of tags are used in EAS systems and include magnetomechanical (also known as acousto-magnetic), radio frequency identification (RFID) and magnetic (also known as magneto-harmonic) tags.
EAS systems present a variety of challenges, including providing gates that generate sufficient magnetic drive fields to fully cover the area between two gates; designing or placing tags that are not easily shielded from a magnetic drive field generated by the EAS gates; and providing cost-effective EAS gates and tags that are proportional in value to the merchandise or media they are being used to track.